data = list(map(float, input().split()))
print(((data[2]-data[0])**2+(data[3]-data[1])**2)**0.5)
 data = list(map(float, input().split())) data list(map(float, input().split())) list map(float, input().split()) map float input().split() ().split () input split print(((data[2]-data[0])**2+(data[3]-data[1])**2)**0.5) print ((data[2]-data[0])**2+(data[3]-data[1])**2)**0.5 (data[2]-data[0])**2+(data[3]-data[1])**2 (data[2]-data[0])**2 data[2]-data[0] data[2] data 2 data[0] data 0 2 (data[3]-data[1])**2 data[3]-data[1] data[3] data 3 data[1] data 1 2 0.5 data = list(map(float, input().split())) list(map(float, input().split())) data
data = list(map(float, input().split()))
print(((data[2]-data[0])**2+(data[3]-data[1])**2)**0.5)

